Portable magnetic test apparatus for converting alternating current to direct current with means to cool the components

ABSTRACT

A small, lightweight, compact, portable magnetic particle inspection unit having a full-time use duty cycle that delivers at least 400 amperes of half-wave direct current to a pair of test prods. The unit includes a transformer having a high voltage primary winding and a low voltage secondary winding that is connected to the test prods. A rectifier is provided for converting the secondary winding low voltage alternating current to pulsating direct current. A relay having a relay coil is connected in series with the primary winding and a switch is provided in series with the relay coil. The test prods are supported in a spaced apart position and the switch is supported near the test prods to provide a convenient method for turning on and off the current in the test prods. The diode of the rectifier is placed directly in the airflow path of a cooling device. The secondary of the transformer is connected to terminal jacks and the test prods are connected by flexible leads to plug in jacks.

United States Patent [721 Inventors Willie P. Ptomey 2294 Janette Drive,Napa;

Leland E. Broyles, 1066 Ross Circle, Napa,

Calif. 94558; James E. llein, 301 Dryden Drive, Vallejo, Calif. [211App]. No. 809,879 [22] Filed Mar. 24, 1969 [45] Patented June 29,1971

Continuation-impart of application Ser. No.

676,302, Oct. 18, 1967.

[54 PORTABLE MAGNETIC TEST APPARATUS FOR CONVERTING ALTERNATING CURRENTTO DIRECT CURRENTWITH MEANS TO COOL THE 2,481,937 9 1949 Mages 324/382,644,921 7/1953 LewkowskiJrH". 324/38 3,346,778 10/1967 Schroeder et al324/38 ABSTRACT: A small, lightweight, compact, portable magneticparticle inspection unithaving a full-time use duty cycle that deliversat least 400 amperes of half-wave direct current to a pair of testprods. The unit includes a transformer having a high voltage primarywinding and a low voltage secondary winding that is connected to thetest prods. A rectifier is provided for converting the secondary windinglow voltage alternating current to pulsating direct current. A relayhaving a relay coil is connected in series with the primary winding anda switch is provided in series with the relay coil. The test prods aresupported in a spaced apart position and the switch is supported nearthe test prods to provide a convenient method for turning on and off thecurrent in the test prods. The diode of the rectifier is placed directlyin the airflow path of a cooling device. The secondary of thetransformer is connected to terminal jacks and the test prods areconnected by flexible leads to plug in jacks.

PATENTED M29 ml SHEET 1 [IF 3 INVENTORS WILLIE P. PTOMEY LELAND E.BROYLES JAMES E. HEIN M7 8 ATTORNEY PATENTEU JUN29 |97| 3. 590 367 sum 3OF 3 Fig.6

Fig. 7

This a continuation-in-part of patent application Ser. No. 676,302,filed Oct. 18, 1967 by Willie P. Ptorney and Leland E. Broyles'entitledHigh Amperage Amplifier."

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

The present invention relates to magnetic inspection equipment and moreparticularly to portable lightweight magnetic inspection equipment.

The inspection of materials by means of magnetic inspection is known tothose skilled in the art. This inspection process involves the use ofequipment that generates a pulsating DC current that is typicallyapplied with a pair of prods to the object being examined. Prior toapplying the DC current to the object, particles that may be magnetized,such as iron filings, are sprinkled on the surface of the object to beexamined. Then the pulsating DC current is applied to the object and theiron filings orient themselves along the lines of force of the magneticfield induced into the object by pulsating DC current. If a defect orflaw exists in the object being examined,

then the lines of force of the magnetic field will be distorted and theiron filings will occupy positions that follow this distortedorientation. By visual inspection it can be seen that the iron filingsare distorted from the normal patternand it is then known that thematerial being examined has a defect.

The primary disadvantages of previous equipment used for this purposewas that it was quite cumbersome and heavy and was not truly portable.As a result, most inspection was done by two-man teams at considerableexpense.

The present invention overcomes this disadvantage in that a small,lightweight, compact, portable magnetic particle inspection unit isprovided which has a full time use duty cycle and will deliver at least400 amperes of half-wave direct current to the prods through a pair ofcables. This has been accomplished by developing an electrical circuitand cooling system which will produce high amperage low voltage halfwavedirect current and at the same time be compact,

lightweight and portable. For example, one such complete unit weighsabout 27 pounds and has aphysical size of 6" 8 12" which permits accessto confined spaces. The meter circuit of the present invention isdesigned so that if a component'fails, such as the rectifier, there isno DC output and therefore no reading of the meter as is desirable.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic diagram of the electrical circuit of the presentinvention;

FIG. 2 is an illustration of the invention;

FIG. 3 is a schematic diagram of the physical positioning of thecomponents of the present invention;

FIG. 4 is an illustration of the physical positioning of the componentsof another embodiment of the present invention;

FIG. 5 is a top elevation of FIG. 4;

FIG. 6 is a front view of FIG. 4 showing the front panel;

FIG. 7 is a rear view of FIG. 4 showing the rear panel; and

FIG. 8 is a side view of FIG. 4 showing the side panel.

In FIG. 1 is illustrated the electrical circuit of the presentinvention. An alternating current power source, such as a l volt,60-cycle per second, power source, is applied to the input terminal 11and 13. Terminal 11 is connected to terminal 15 and terminal 13 isconnected to terminal 17 of main power switch 19. Terminals 21 and 23are applied to opposite sides of electric fan motor 25. Terminal 23 isconnected to one side of current limiting resistor 27, to terminal 29 ofrelay 31 and prod element of the present to terminal 33 of pushbuttonswitch 35. Terminal 34 of pushbutton switch 35 is connected to one endofrelay coil 37. Terminal 21 is connected to one side of neon lamp 39, tothe other end of relay coil 37 and to terminal 41 of relay 31. Relay 31includes an elongated core 32 i as indicated by dotted lines.

, One end of the elongated core is operatively associated with relaycoil 37 and the other end is connected to switching elements 42 and 44.Terminals 43 and 45 are respectively applied to opposite ends of primarywinding 47 of transformer 49.

Terminal 51 of secondary winding 52 is connected to the cathode of diode53 and terminal 54 of the secondary winding is connected to prod 55. Theanode of diode S3 is connected to one end of shunt 57 and the other endof shunt 57 is connected to prod 59. Ammeter 61 is connected across theterminals of shunt 61 to measure the current flow through the prods -55and 59 when they are operatively connected to the material beingexamined.

In FIG. 2 is shown a more detailed illustration of prod element 103including prods 55 and 59 and pushbutton switch 35. Prods 55 and 59 arerespectively connected to support member 105, which is made ofdielectric material, by means of fastening members 107 and 109. Alsoconnected to fastening members 107 and 109 are heavy gage electricalconductors 91 and 95, respectively. Prod 55 comprises heavy gageelectrical conducting braided wire 110 that is covered by sleeve 111,which is made of electrical conducting material. The narrow end oftapered electrical conducting rod 113 is connected to braided wire 110and to sleeve 111. The broad end of tapered rod 1 13 is flattened out toform a base connecting plate 115. The base connecting plate 115 ispivotally mounted on support member 105 by fastening member 107. Baseconnecting plate 115 has a friction fit with fastening member 105 sothat it may be pivoted about member 107 by the use of sufficient force.However, the friction fit prevents prod 55 from jarring loose from itsposition after it has been pivoted into the desired position. Braidedwire 110 extends from the end of sleeve 111 and this extending braidedwire is used to physically contact the material to be tested. It hasbeen found that this short extension of braided wire from sleeve 111provides a very effective method for providing a good electricalconnection between the prod and the material, especially when largecurrents are involved requiring the exertion of substantial force of thebraided wire against the material being tested. Prod 59 is the same asprod 55 and will therefore not be described. v

The wires 117 and 119, leading to pushbutton switch 35, are I coveredwith dielectric material and may be wrapped in physical contact withheavy gage electrical conductors 91 and 95. Pushbutton switch 35 ispositioned adjacent to the center part of dielectric support member 105so that the operator of the equipment can easily and conveniently applycurrent to prods 55 and 59 by pressing button 121 of pushbutton switch35.

In FIG. 3 is illustrated the position of the various components of themagnetic inspection device. In FIG. 3 is also shown the enclosure havinga bottom panel 63, top panel (not shown), rear panel 65, front panel 67and side panels 69 and 71. Mounted on rear panel is motor-fan housing 73and mounted therein is motor 25 and fan 75. Housing 73 has an openpassage for air which is drawn through an opening provided in rear panel65 and is blown over motor 25 and over diode housing 77 which is mounteddirectly behind housing 73. Diode housing 77 includes cooling fins (notshown) and mounted near its center is diode 53. Mounted behind diodehousing 77 is relay 31, transformer 49 and shunt 57. A heavy gageelectrical conductor 79 is connected between the cathode of diode 53 andterminal 51 of transformer 49. A heavy gage electrical conductor 81 isconnected between the anode of diode 53 and terminal 82 of shunt 57.Heavy gage electrical conductor 83 connects terminal 84 of shunt 57 tofemale terminal 85 and heavy gage electrical conductor 87 is connectedfrom terminal 53 of transformer 79 to female terminal 89. Heavy gageelectrical conductor 91 is connected between male terminal 93 and prod55 and heavy gage electrical conductor 95 is connected between maleterminal 97 and prod 59.

From FiG. 3 it can be seen that housing 77, relay 31, transformer 49,shunt 57 and heavy gage conductors 79, 81, 83, and 87 are positionedsuch that cooling air, as indicated by the broken arrows, uniformlyflows over the components to bring, about maximum effective'cooling.Louvers 99 and 101 are respectively provided in the front region of sidepanels 69 and 71 so that the heated exhaust air may pass therethroughafter having cooled the previously described components.

Typical operation of the previously described magnetic inspection deviceis as follows. The operator applies power to the device by closingswitch 19 which is mounted on front panel 67 (not shown) of the device.The operator then adjusts the position of prods 55 and S9 and braidedwires 110 of the prods against the material to be tested. The operatorthen presses button 121 of switch 35 for a period of from 2l5 seconds,for example, depending upon the currents used and the type of materialsbeing examined. When button 121 is being pushed, causing switch 35 toclose, relay coil 37 is actuated which causes relay 31 to close. Thiscauses AC current to passthrough primary winding 47 of transformer 49.The secondary winding has inducted therein an AC signal that has astepdown in voltage and a step-up in current as compared to the primarywinding. Diode 53 permits only the pulsating DC portion of the ACcurrent in the secondary winding to pass to prods 55 and 59. Thispulsating DC signal is then passed through the prods and through thematerial being tested that is between the prods. While current ispassing through the material, the operator applies magnetic particles tothe material being tested and removes the excess by blowing with a handbulb air applicator, for example. The magnetic particles are typicallypowered iron filings that are dyed for color contrast with the materialbeing tested. Then the current is stopped by releasing button 121 whichcauses switch 35 to open. The pattern of the magnetic particles on thematerial being tested is then examined to determine if there are anyflaws in the material. Typically, the signal passing through the prodsis at about 400 amps and 4.4 volts. However, this will vary primarilydepending upon the resistance of the material between the prods. Thetypical magnetic particle pattern occupies an area about 4 inches longand 2 inches wide.

In FIGS. 4 through 8 is illustrated another embodiment of the enclosureand the components of the present invention. The enclosure includes abottom panel 125, top panel 127, rear panel 129, front panel 131, andside panels 133 and 135. Mounted on the lower side of bottom panel 125are shock mounts 137. Mounted on rear panel 129 is male power receptacle139 and motor fan housing 141 which has mounted therein a motor and fan(not shown) for cooling the various electrical components. Housing 141has an open passage for air which is drawn through opening 143 of rearpanel 129 and is blown over the fan motor and over diode housing 145which is mounted directly behind housing 141. Diode housing 141 includescooling fins (not shown) and mounted on support member 147 near itscenter is diode 149. Transformer 151 and shunt 153 are traverselymounted behind diode housing 141 so that they will receive maximumcooling effect from the circulating air. Relay 155 is offset from themain airflow path since it does not need as much heat dissipation as dothe diode, transformer and shunt. l-leavy gage electrical cables areused for conducting current where large currents are involved.

From FIGS. 4 and it can be seen that diode housing 145, transformer 151,shunt 153, relay 155, and the heavy gage conductors are positioned suchthat cooling air passes over the components to bring about the mosteffective cooling as required by each of the components. As shown inFIG. 8 louvers 157 are provided in the front region of side panels 133and 135 so that the heated exhaust air may pass therethrough afterhaving cooled the previously described components.

Mounted on front panel 131 is ammeter 159, pilot light 161, main powerswitch 163, two female connectors 165 and 167 for connection with themale connectors of the heavy gage pushbutton switch 35.

cable of probes 55 and 59. Also provided on front panel 131 is remotecontrol connector 169 which is used to provide a convenient disconnectpoint for wires 117 and 119 leading to The operation of the embodimentshown in FIGS. 4;- through 8 is similar to that described in referenceto FIGS. 1 through 3.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. it is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What we claim is:

1. A portable magnetic testing apparatus for converting alternatingcurrent to a low voltage high amperage direct current, said apparatuscomprising:

first and second power terminals for being operatively connected to analternating current source;

a transformer having a single primary winding and a single secondarywinding;

said primary winding having first and second terminals;

a first conductor connecting said first power terminal and said firstterminal of said primary winding;

first and second switches operatively connected in series in said firstconductor;

a second conductor connecting said second power terminal and said secondterminal of said primary winding;

third and fourth switches operatively connected in series in said secondconductor;

said first and third switches being operatively interconnected and saidsecond and fourth switches being operatively interconnected;

a relay having a relay coil and an elongated core, one end of saidelongated core being operatively connected to said second and fourthswitches and the other end of said elongated core being operativelyassociated with said relay coil;

a third conductor operatively connecting one end of said relay coil andsaid first conductor at a position between said first and secondswitches;

a fourth conductor operatively connecting the other end of said relaycoil to one terminal of a pushbutton switch and a fifthconductoroperatively connecting the other terminal of said pushbutton switch andsaid second conductor at a position between said third and fourthswitches;

first and second prods;

said single secondary winding having first and second terminals;

a sixth conductor connecting said first terminal of said singlesecondary winding to said first prod;

a single diode;

a seventh conductor operatively connecting said second terminal of saidsingle secondary winding to the cathode of said diode;

an eighth conductor operatively connecting the anode of said diode tosaid second prod; and

said first and second prods being mounted in fixed spaced relation on ahandle and said pushbutton switch being operatively connected to saidhandle between said fist and second prods;

each of said prods comprising electrical conducting braided wires thatare partially covered by a sleeve of electrical conducting material, thebraided wire of each of said prods extending beyond one end of said eachof said sleeves, the other end of each of said sleeves is flattened andpivotally mounted on said handle;

a housing having an air inlet opening and a cooling means,

said cooling means comprising a fan and motor positioned adjacent saidinlet opening for drawing air through said inlet opening and dischargingit into said housing, said rectifier comprising a diode mounted in adiode housing having cooling fins, said diode and diode housingpositioned directly behind said fan and in the path of the airdischarged from said fan, said transformer and relay at the end oppositefrom said air inlet opening for discharging the cooling air after it hascooled said diode, diode housing, transformer and relay.

1. A portable magnetic testing apparatus for converting alternatingcurrent to a low voltage high amperage direct current, said apparatuscomprising: first and second power terminals for being operativelyconnected to an alternating current source; a transformer having asingle primary winding and a single secondary winding; said primarywinding having first and second terminals; a first conductor connectingsaid first power terminal and said first terminal of said primarywinding; first and second switches operatively connected in series insaid first conductor; a second conductor connecting said second powerterminal and said second terminal of said primary winding; third andfourth switches operatively connected in series in said secondconductor; said first and third switches being operativelyinterconnected and said second and fourth switches being operativelyinterconnected; a relay having a rElay coil and an elongated core, oneend of said elongated core being operatively connected to said secondand fourth switches and the other end of said elongated core beingoperatively associated with said relay coil; a third conductoroperatively connecting one end of said relay coil and said firstconductor at a position between said first and second switches; a fourthconductor operatively connecting the other end of said relay coil to oneterminal of a pushbutton switch and a fifth conductor operativelyconnecting the other terminal of said pushbutton switch and said secondconductor at a position between said third and fourth switches; firstand second prods; said single secondary winding having first and secondterminals; a sixth conductor connecting said first terminal of saidsingle secondary winding to said first prod; a single diode; a seventhconductor operatively connecting said second terminal of said singlesecondary winding to the cathode of said diode; an eighth conductoroperatively connecting the anode of said diode to said second prod; andsaid first and second prods being mounted in fixed spaced relation on ahandle and said pushbutton switch being operatively connected to saidhandle between said fist and second prods; each of said prods comprisingelectrical conducting braided wires that are partially covered by asleeve of electrical conducting material, the braided wire of each ofsaid prods extending beyond one end of said each of said sleeves, theother end of each of said sleeves is flattened and pivotally mounted onsaid handle; a housing having an air inlet opening and a cooling means,said cooling means comprising a fan and motor positioned adjacent saidinlet opening for drawing air through said inlet opening and dischargingit into said housing, said rectifier comprising a diode mounted in adiode housing having cooling fins, said diode and diode housingpositioned directly behind said fan and in the path of the airdischarged from said fan, said transformer and relay positioned behindsaid diode housing and parallel with respect to the airflow path afterit has cooled said diode and diode housing and louvers positioned insaid housing at the end opposite from said air inlet opening fordischarging the cooling air after it has cooled said diode, diodehousing, transformer and relay.